todo updated
todo renamed
make annotators to accept empty seq lists
calculate_stats now uses SeqItems for fastq files
refactoring: seq functionality moved to its own module
count_seqs_in_files removed. It was a duplicated functionality.
split_mates moved to SeqWrapper SeqIO
change_case moved to SeqWrapper SeqIO
trim_blast_short moved to SeqWrapper SeqIO
sff_extract moved to SeqWrapper SeqIO
read and write seqrecords are now private